Mechanisms of Estrogen Signaling and Neuroprotection

描述（由申请人提供）：172-雌二醇（E2）被认为在多种神经退行性疾病中发挥神经保护作用，包括中风；然而，其在大脑中的非基因组和基因组信号传导机制及其神经保护作用尚不清楚。我们小组的工作可能会通过我们克隆一种新的内质网共调节因子PELP1来阐明这个问题，我们认为PELP1是解释E2在大脑和神经保护中诱导非基因组和基因组信号的能力的关键“缺失环节”。为了验证我们的假设，Aim 1将使用PELP1前脑特异性KO （PELP1 FB KO）小鼠模型来确定PELP1在脑缺血后E2非基因组和基因组信号、抗氧化作用和大脑神经保护作用中的作用。由于对PELP1在大脑中的调控知之甚少，Aim 2将表征脑缺血后大脑中PELP1的表达、磷酸化和信号体的形成，确定E2的调节作用，并鉴定负责PELP1磷酸化的激酶。初步数据表明，PELP1也可能通过调节脑芳香化酶启动子的激活，在调节脑局部E2产生中发挥重要作用。因此，Aim 3将通过使用PELP1 FB KO小鼠来检测PELP1敲除对基础和e2诱导的脑内芳香化酶表达和活性的影响，并确定PELP1调节的特异性脑芳香化酶启动子。ChIP还将评估PELP1向脑芳香化酶启动子的募集情况，同时还将研究局部E2产生在通过低生理水平E2增强神经保护作用中的潜在作用。最后，Aim 4将验证在一段时间的E2长期剥夺（如绝经后）后E2神经保护能力的丧失是由于PELP1和/或ER1的脑特异性表观遗传基因沉默造成的，并将确定基因沉默是否可逆以及E2敏感性是否可以在大脑中恢复。拟议的研究有可能显著推进我们对E2如何在大脑中发挥其信号传导和神经保护作用的理解，并可能提供E2在WHI研究中未能发挥有益心血管和神经作用的机制理解，在WHI研究中，E2替代在绝经开始后很久就开始了。

DESCRIPTION (provided by applicant): 172-Estradiol (E2) has been implicated to exert neuroprotection in a variety of neurodegenerative disorders, including stroke; however, the mechanisms underlying its nongenomic and genomic signaling in the brain, and its neuroprotective effects remains unclear. Work by our group may shed light on this issue via our cloning of a novel ER coregulator, called PELP1, which we propose is the critical "missing link" that explains E2 ability to induce both nongenomic and genomic signaling in the brain and neuroprotection. To test our hypothesis, Aim 1 would use a PELP1 forebrain-specific KO (PELP1 FB KO) mouse model to determine the role of PELP1 in E2 nongenomic and genomic signaling, antioxidant actions, and neuroprotective effects in the brain following cerebral ischemia. Since little is known about the regulation of PELP1 in the brain, Aim 2 would characterize PELP1 expression, phosphorylation and signalsome formation in the brain following cerebral ischemia, determine the regulatory role of E2, and identify kinases responsible for the phosphorylation of PELP1. Preliminary data suggest that PELP1 may also play an important role in regulating local E2 production in the brain by regulating activation of the brain aromatase promoter. Thus, Aim 3 would examine the effect of PELP1 knockout on basal and E2-induced aromatase expression and activity in the brain through use of PELP1 FB KO mice, and identify the specific brain aromatase promoter regulated by PELP1. Recruitment of PELP1 to the brain aromatase promoter would also be assessed by ChIP, and the potential role of local E2 production in amplifying neuroprotection by low physiological levels of E2 would also be examined. Finally, Aim 4 would test the hypothesis that loss of E2 neuroprotective ability after a period of long-term E2 deprivation (such as occurs after menopause) is due to a brain-specific epigenetic gene silencing of PELP1 and/or ER1, and would determine whether the gene silencing is reversible and whether E2 sensitivity can be reinstated in the brain. The proposed studies have the potential to significantly advance our understanding of how E2 exerts its signaling and neuroprotective effects in the brain, and may provide a mechanistic understanding of why E2 failed to exert beneficial cardiovascular and neural effects in the WHI study, where E2 replacement was begun long after the onset of menopause. PUBLIC HEALTH RELEVANCE: Estrogen (E2) has been implicated to exert neuroprotection in a variety of neurodegenerative disorders, including stroke. This proposal would elucidate the mechanisms underlying E2 neuroprotection in the brain and potentially provide a mechanistic explanation as to why the Women's' Health Initiative (WHI) studies failed to observe beneficial effect of E2.